Reduction mechanism of indonesian limonite ore by solid reducing agents

Limonite ore from Sulawesi Island (Indonesia) was reduced isothermally at 900 - 1200 degrees C by pulverized coal and charcoal to produce ferronickel. XRD and XRF analyses were used to characterize the samples. The influence of reductive conditions on the reduction and metallization degree of the samples, including reduction temperature, reduction time and reducing agent types were studied. Results have shown that both the reduction and metallization degrees increase as temperature and time increase. The reduction reactions will be more completed at higher reduction temperature. It could be seen from XRD results that magnetite and Fe-Ni peaks increased at higher temperature reduction. This could be mean that the rate of reduction reaction is faster at higher temperature. The losses of samples weight also happen faster at higher temperature. It was also found that the reduction behaviors using coal differed from those using wood charcoal due to the differences in proximate content. From this study, it could be concluded that fixed carbon content in the reducing agent did not always be the most important aspect of choosing a reducing agent. The sample which has been reduced with coal and charcoal showed an almost exactly same pattern even they both had different characteristics. The relatively higher volatile matter content in charcoal gave a significant contribution to the reduction process.